Main cylinder release and pump bypass valve



Dec. 30, 1941. w. ERNS'II' 2,268,205

MAIN CYLINDER RELEASE AND PUMP BY-PASS VALVE- Filed July 24, 19,39 2 Shee'tS Shee't 1 JVALTER 10151;

W.i I W Patented Dec. 30, 1941 MAIN CYLINDER RELEASE AND PUMP BY PASS VALVE Walter Ernst, 'Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. Inc., Wilmlngton, Del., a corporation of Delaware Application July 24, 1939, Serlal No. 286,083 I (Cl. 137-153) a 2 Claims.

This invention relates to hydraulic machinery, and in particular, to valves.*

One object of the invention is to provide a valve which permits a controlled release of hydraulic pressure from the main cylinder of a hydraulic press upon the reversal oi the main plunger after the completion of vthe pressing stroke.

Another object is to provide a main cylinder release and by-pass valve operative to gradually release hydraulic pressure from the main cylin- V der of a hydraulic press immediately after the reversal of the main plunger upon the completion of the pressing stroke, and at the same time to momentarily by-pass the discharge of the pump which supplies the circuit with pressure fluid until the pressure is completely released from the main cylinder, after which the valve shifts to permit the pressure to buildup in the pull-back circuit and return the main. plunger to its retracted position.

Another object is to provide a main cylinder release and pump by-pass valve having a pair of valve plungers in a casing arranged .in such a manner so that one plunger automatically shifts to release pressure from the main cylinder oi!v the press upon the reversal oi thepump supplying the press, this release taking place gradually so as to avoid shock, while at the same time the pump discharge is temporarily by-passed until the pressure is completely released from the main cylinder, after which the other valve plunger automatically closes to permit the building up 01' pressure in the pull-back circuit and the consequent return of the main plunger to its retracted position.

In the drawings:

Figure 1 is a central vertical longitudinal section through the main cylinder release and pump by-pass valve of this invention, taken in a plane a casing having a pair of valve plungers, with the valve chamber of one plunger connected (Figures 1 and 3).

the valve bore l|- serves as an operating chamto an operating chamber adjacent the end of the other valve plunger. When the pump is reversed to admit pressure fluid to the pull-back line, this automatically shifts the first valve plunger into a position where it discharges pressure from the main cylinder through a needle valve. This gives a controlled release oi. hydraulic pressure from the main cylinder upon the reversal of the main plunger after the pressing stroke. At the same time the other valve plunger is held open as long aspressure still stands in the main cylinder circuit, thereby temporarily by-passing the discharge of the pump. When pressure has been completely released from the main cylinder circuit the second valve plunger closes, cutting of! the temporary bypass and permitting pressure to build up in the pull-back line, thereby reversing the main plunger.

Valve construction Referring to the drawings in detail, Figure 1 shows the main cylinder release and by-pass valve, generally designated 9, as consisting of a casing l having a pair oi. bores H and I2, in which reciprocate a pair of plungers l3 and Il, respectively. The plunger [3 consists of a stem l5 having two heads l6 and I1 reciprocable in the bore I l, and a third head l8 reciprocable in a counterbore l9. Beyond the head 18 the stem terminates in an extension 20 surroundedby a coil spring 2|. Thelatter engages the head I8 at one end, and the inner wall of a hollow cap 22 at its other end. The cap 22 is provided with ,a threaded portion 23 engaging the threaded bore 24 coaxial with the bores l9 and II. By rotating the cap 22 the force of the compression spring 2| upon the valve plunger 13 may be varied. 1

The valve bore ll opens into a central chamber 25, to which fluid is admitted through a threaded port 26 from the main cylinder branch line 21. The right-hand end of the bore II is provided with a connection 28 for securing thereto the end of the pull-back branch line 29 Thus the right-hand end.oi

ber 30 for shifting the valve plunger l3 by pressure fluid acting against the right-hand end of the head It on the valve plunger l3. The valve bore II also opens into a discharge chamber 31 (Figures 1 and 2), from which the passageway 32 runs to a tapered discharge port 33, the passageway 32 being closed at its outer end by a plug 34 threaded into the threaded bore 35.

The tapered discharge port 33 is configured to receive the correspondingly tapered end 36 of a needle valve member,generally designated base 42 oi theoperating rod 48. The latter is provided at its upper end with a hand wheel 44 (Figure 3), by which the needle valve member 81 control the rate of release of the fluid. The counterbore I9 is provided with a pair of ports 45 and 48 for the discharge or fluid leaking past the heads l1 and i8, respectively.

The casing 10 is provided witha diagonal ridge 41 containing a passageway 48 (Figures 2 and 3) runningtrom a port 49 opening out of the chamber 25 to a port 50 opening into the threaded counterbore forming an end chamber and extension of the valve bore I 2. The end of the threaded counterbore 5| is closed by a threaded plug 52 inserted therein. The valve bore I2 is provided with a central exhaust chamber 53, from which exhaust ports 54 extend outward through the casing l8 (Figure 3). The valve bore l2 on either side of the chamber 53 is provided with counterbores 55 and 58, having sleeves 5! and 58 mountedtherein and constituting seats for the valve plunger l4. The sleeve 51 is slidably engaged by a piston head 59 on the valve plunger l4, whereas the sleeve 58 is slidably engaged by a fluted portion 80 thereon, and terminating in a head 8|. The fluted portion 68 is provided with four flutes 82, through which fluid can pass. The end of the sleeve 58 serves as a port 63, which is closed by the head 8| (Figure 1). The port 83 opens into a chamber 84, which extends down to the port 83 from the valve bore II and contains the head 8| on the valve plunger l4. Beyond the counterbore 55 and the chamber 84 the casing I8 is provided with a threaded port 85, closed by a threaded plug I may be rotated and the annular space between I the tapered bore 38 and the tapered end 88 of the needle valve member may be varied so as to 68. The threaded plugs 52 and 86 permit access to the valve plunger M. The port 58 (Figure 2) is closed at its outer end by a threaded plug 81. The casing I0 is provided with integral feet 88 for supporting the valve upon the floor of the tank in which it is placed. A port 69 opens out of the chamber 84 and serves for the connection of a conduit running to the operating chamber of the surge valve, as hereinafter described.

Valve circuit A typical circuit in which the main cylinder release and pump by-pass valve of this invention may be employed is shown in Figure 3. This circuit includes the main cylinder release and bypass valve 9 of the invention, supported by its feet 88 upon the shelf 18 forming a part of the main cylinder "It (Figure 3), and likewise forming a support for the bottom of the surge tank 12' in which the valve 9 is placed. The main cylinder H is provided with a cylinder bore 13 having the piston head It of, the main plunger 15 reciprocable therein. The head of the main cyling it.

The main cylinder bore it is provided with upper and lower ports 86 and 89, on opposite sides of the main plunger head it. The conduit as i the casing I 8. Secured to the needle valve me'mber 8'l, as bythe cotter pin 4| (Figure 2), is the runs from the port 88 to the connection 88 of the variable delivery pump 84,. The conduit 82 is likewise connected tothe conduit 21 running to the upper port 28 in the valve casing l8, previously referred to. Running Iromthe lower port 8| in the main cylinder II is a conduit leading to the connection 88 of the variable delivery .pump 84, opposite the connection 88. The conduit 85 is likewise connected to the conduit 29 running to the end of the valve bore ll (Figure 1) The variable delivery pump 84 is of any suitable type, the type illustrated being described and claimed in the copending application of Waltel Ernst, Ser. NO. 186,859, flled January 25, 1938,

and is controlled by a servomotor 81 as regards the quantity and direction of its delivery.

The variable delivery pump 84 consists of a cylinder barrel having radial cylinder boreswith pistons engaging a secondary rotor, rotatable up on an axis decentered from the axis of rotation of the cylinder barrel so that the pistons are thereby reciprocated in the cylinders. The distance of decentration of the axes of. rotation of the cylinder barrel and secondary rotor, respectively. may be varied by moving the shift ring surrounding the secondary rotor. This shift ring is connected to the servomotor 81 and shifted thereby. The servomotor 81, in turn, is under the control of a servomotor control valve 88, which is connected as at 89 (Figure 3) to a rocking lever 90 supported upon a floating link 9!.

The lever 90 may be shifted into the different positions indicated in Figure 3 so as to provide a forward or reverse delivery or fluid, or the cylinder barrel and secondary-rotor may be caused to rotate upon a common axis of rotation when the lever 90 is in the position marked Neutralf' (Figure 3). When the lever 80 is shifted to the position marked Forward the pump connection 88 delivers pressure fluid into the conduit 82 and the connection 85 becomes a. suction connection,

withdrawing fluid from the conduit 85. When placed in suction and the connection 88 and conduit 85 are placed under pressure.

The opposite side of the pump 84 is provided with a safety centering device 92, described in Ernst application, Ser. No. 170,250, flied October 21, 1937, and forming no part of the present invention. The lower endof the cylinder bore 78 is provided with a port 93, from which the conduit 94 runs to a check valve 95 within the,

surge tank 12.

' Operation In the operation of the main cylinder release and pump by-pass valve of this invention, the pump 8% is placed in position for forward delivery by shifting the lever 98 to the position marked Forward." Pressure fluid is then discharged through the port 88, into the space above the main plunger head it, and is withdrawn from the space beneath the latter through the port 8%. The main plunger F5 then descends to perform its pressing stroke, and the surge valve it automatically opens to prefill the space above the head it until, resistance is encountered, whereupon the surge valve if? automatically closes and pressure is built up above the head it to perform the pressing stroke. While the plunger 75 is performing the pressing stroke a portion of the pressure fluid enters the central chamber 25 of the valve 5, through the conduit Zi. This pressure fluid, however, acts against the equal annular areas of the valve heads [6 and I1, hence, one pressure balances the other and the valve plunger l remains immovable. A portion of this pressure fluid passes through the port 49, the passageway 48 and the port 50, into the end chamber 5| of the valve bore I2, acting against the end of the head 59 and shifting the valve plunger l4 to the right so that the head 6| uncovers the port 63 and opens communication between the chamber 64 and the ex haust chamber 53.

When the pressing stroke has been completed, the reversible variable delivery pump 84 is reversed by shifting the lever 90 to the position marked Reverse, whereupon pressure fluid is now deliveredintothe conduits 85 and 29 and withdrawn from the conduits 80 and 21. The shock of reversal which would otherwise occur from the presence of the high pressure in thespace above the main plunger head 14 is prevented by the action of the main cylinder release and by-pass valve 9. As soon as the pump 84 is reversed, the pressure fluid supplied to the pull-back conduit 85 likewise passes intothe'branch conduit 29 and into the right-hand end of the upper valve bore II, where it acts against the end 30 of the head l3, and shifts the valve plunger I5 to the left by compressing the spring 2|. The consequent shifting of the head I! to the left opens communication between the chambers 25 and 3|. Pressure fluid then escapes from the space above the main plunger head 14, through the port 80, the conduits 8-2 and 21, the chambers 25 and 3|, the passageway 32 (Figure 2) and the needle valve port 33. This needle valve port 33 provides a gradual release of the pressure fluid from the main cylinder, and prevents the shock which would otherwise occur.

Meanwhile, since there is pressure still standing in the valve chamber 25, the valve plunger i4 is held in its position shifted to the right and opening communication between the chambers 54 and 53. Under these circumstances the pump discharge is temporarily by-passed through the conduit 29, the end chamber 30, the chamber 64, the port 63 and the exhaust chamber 53, through the exhaust ports '54, into the surge tank 12. Thus the pump discharge is temporarily bypassed while the release of pressure in the main cylinder ll takes'place. When this release has been entirely completed so that the pressure in ration between its tapered end 35 and the tapered port 33. This opening is adjusted until no shock occurs in the system. Without the needle valve 31 the direct discharge of the pressure fluid would permit the release of pressure too quickly from the main cylinder, thereby causing shock to the pressure system unless the outlet port were made of a'very small diameter. The provision of the needle valve enables the size of this port to be adjusted according to the most favorable circumstances.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A release and by-pass valve comprising casing means having, a release valve boreand a by-pass valve bore. each bore having inlet and outlet chambers, a release valve member and a by-pass valve member in said release valve bore and by-pass valve bore respectively, an'operating chamber associated with, each valve member, each valve member having means thereon for selectively interconnecting and disconnecting said inlet and outlet chambers, means for yieldingly urging said release valve member in one direction, means responsive to the admission of pressure fluid to said release-valve-operatingchamber for urging said release valve member in the opposite direction, means responsive to the admission of pressure fluid to said release valve inlet chamber for shifting said 'by-pass valve member to its by-passing' position, and means subjecting the by-pass valve directly to the hydraulic pressure of the release valve operating chamber when the release valve is shifted to open position, for closing the by-pass valve when pressure subsides in the release valve inlet chamber.

2- A release and by-pass valve comprising a casing having a release valve bore and a by-pass valve bore therein, each bore having inlet and outlet ports, a release valve member movable in one direction in said release valve bore by yield- -ing means and in the opposite direction by hydraulic means for controlling said release .valve inlet and outlet ports, a by-pass valve member arranged in said by-pass valve bore and movable therein in opposite directions respectively by a the main cylinder and end chamber 5| has dropped to zero, the valve plunger I4 will shift to the left, under the influence of ,the pressure fluid in the chamber 54, causing the head 5| to close the port 53. With the outlet of the chamvalve head and a hydraulically operable piston, operating chambers associated with each valve member, said by-pass piston being operable by fluid admitted through said release valve inlet port, and means subjecting the by-pass valve directly to the hydraulic pressure of the release valve operating chamber when the release valve is shifted to open position, for closing the bypass valve when pressure subsides in the release valve inlet chamber, said by-pass valve being closed solely by the hydraulic pressure in said chamber.

WALTER ERNST. 

